Thousands of spam subscribers

I have just taken over maintaining a neglected wp with bp site theculinarytrust.org . I have updated to wordpress 3.5.1 and buddypress 1.6.4 and all is working well. The problem is with the site’s subscribers. There are over 35,000 subscribers, most of which are sploggers. I’ve been using WangGuard for the last week or so, and it does a great job spotting new splog signups. The problem is all the old subscribers. I’ve tried the WangGuard wizard, but it does not get anywhere near the number of sploggers I need removed.

Is there some plugin that could help me filter out human subscribers? Is there some way to send an email to all subscribers to verify their humanity!?

How you said, WangGuard works great for protect your website and with the Wizard you can check many of the old ones. But every website is different and WangGuard knows many old Sploggers, but not all of them. WangGuard is only 1 year an 11 month old (today).

The first year blocked 750.000 sploggers, and in the in the next 11 months, 5.000.0000 sploggers. You can see that its growth is exponential.

About your question if there is a tool for check the humanity of your old users… I’m sorry but only WangGuard. WangGuard is the only tool out there to check users